“Agents” of deterioration - abc methods in risk management

71 An aid, not a straitjacket

At some point, every user notes that the 10 agents are a simplification of a complex reality. From the perspective of the heritage asset, fire can split into incorrect

temperature, pollutants, and incorrect humidity, and later water and dissociation. Large floods may be better classified outside the agents’ framework rather than split into water and physical forces and incorrect relative humidity (RH). It’s up to you to choose.

As with any conceptual tool, if it becomes more nuisance than aid, it can be adapted or dropped. With long experience, however, and the need for efficient strategies, one does keep coming back to these 10 agents.

See the CCI web page for details

The 10 agents of deterioration are each explained in great detail on the CCI web page.

The causal chain from hazard to adverse effect, via the 10 agents

Causality: Our overall model

The yellow, red, and white rectangles in the diagram below are some of the words and phrases that people give during a group exercise when asked simply “What are the risks to my heritage asset?” followed by “What are the causes of each risk?” and “What are the effects of each risk?” The phrases elicited can always be organized as shown, with arrows linking phrases. These cause-and-effect arrows all flow left to right, from external hazards or internal hazards via failures of resources, failures of mitigation, via the agents of deterioration, ending in an adverse effect on the asset. Each path from its beginning on the left to its end on the right constitutes a risk scenario.

© Government of Canada, Canadian Conservation Institute. CCI 96638-0035 Figure 9. The cause and effect chains that form during the group exercise that asks simply “What are the risks to my heritage asset?” followed by “What are the causes of each risk?” and “What are the effects of each risk?” It demonstrates that the many phrases elicited by the word “risks” form links in a network of cause and effect beginning with hazards and ending with effects on the asset.

The agents of deterioration as a complete set of organizers

The agents of deterioration (red boxes) serve as channels to organize all the scenario paths and are located at the interface with the items themselves (the grey rectangle).

The three “Types” of risk occurrence

In terms of occurrence (timing), risks can be divided into two main groups: events and cumulative processes. For practical purposes, events can be further divided into rare and common events. The result is three practical types of risk occurrence: rare events, common events, and cumulative processes. The boundaries between the three

categories are not precise; each overlaps with the next category. The purpose of the

“types” framework is to guide the risk discovery process, to guide the location of information during the analyze risks step, and to guide thinking during the treat risks step.

These three types of risk occurrence do not imply anything about the size of the risk — your smallest risk and your largest risk, and everything in between, can be any one of the three types.

Table 7. The three types of risk occurrence.

Rare events Common events Cumulative processes

“Rare” events occur less often than approximately once every 100 years (from the perspective of one heritage organization.) As a result, rare events are not part of the direct experience of most heritage

organization staff. From the perspective of the total heritage of a nation, such events may happen every few years, and from a global perspective, these events can become routine.

Common events occur many times per century.

These are events that are part of the direct experience of many heritage

organization staff or of people in the vicinity of the heritage organization.

Cumulative processes can occur continuously or intermittently. Over the years, most heritage organization staff will have observed the cumulative effect of one or two such processes on some items, that is to say, they will have seen the item “age.” Very frequent events (more than once a year) can also be considered as cumulative processes for risk analysis.

Examples:

Floods

Damaging earthquakes Large fires

Theft

Visitor knocking over a special item

Examples:

Water leaks

Damaging earthquakes (some parts of the world) Small fires

Collapse of overloaded furniture

Many handling “accidents”

“Petty” theft

Examples:

Yellowing of newsprint Fading of some colours Corrosion of metals Erosion of stone Abrasion by visitors

“Rare” as a rigorously defined term

Rare is relative to the time horizon

Rare can be defined precisely as events that occur less often than the selected time horizon of the risk assessment. For example, if one selects a 100-year time horizon, then rare events are those which have a mean time between events of more than 100 years. If one selects 30 years, then rare events are those that have a mean time between events of more than 30 years.

Implications for the idea (feeling) of risk

Rare events are not a “sure thing.” We think of them in terms of “chance” of happening.

Common events and cumulative processes are a sure thing. Note that the distinction can only have meaning if we specify a particular time horizon and a particular heritage asset…very little that is plausible is rare if we speak of all heritage organizations and many centuries.

This distinction was noted already in the general discussion of the equivalence of definite fractional loss with the chance of total loss. Decision makers may have a “gut feeling” that a 5% chance of losing the entire heritage asset and a definite loss of 5% of the heritage asset are not equivalent, but the method assumes that they are equivalent.

The method will, of course, always make clear to decision makers which risk is a chance and which is a “sure thing” from the perspective of their planning cycle, their organization. (As noted before under uncertainty, in reality even a “sure thing” is clouded by some degree of uncertainty.)

Implications for the calculation of risk

If the mean time between events is longer than the time horizon selected, then these are events that one should express as a probability, rather than a frequency or mean time between events. This makes for a subtle distinction — the probability of such

events within the time horizon is not 1, i.e. it is not “guaranteed.” It is less than 1. For the standard assumption of a “normal” distribution of probabilities, for example, the

probability that a 100 year event will occur in 100 years is only 0.6.

Not an issue

The necessary precision in both the conception and the calculation of rare risk is beyond the scope of the ABC method and, fortunately, not significant to the kinds of distinctions between large and small risks that we seek to uncover for heritage assets.

As long as one consistently expresses all events in terms of frequency, even when it seems bizarre, then risk calculations will be correct. For example, regional data may suggest that the probability of a certain natural hazard is 1% in 100 years; this can be expressed as its equivalent frequency of “once every 10,000 years.”

The five “Stages” of control

1. Avoid

Avoid is the first logical stage and the most effective if feasible. Avoiding attractants is an important aspect of reducing pest risk, but avoiding whatever natural disasters fate has in store, other than by moving the heritage asset, is impossible.

2. Block

A barrier, somewhere between the source of the agent and the item, is probably the single most practical element of reducing risks from all agents.

3. Detect

Avoid and block will eventually fail; one needs an appropriate degree of detection for each agent or for its effects.

4. Respond

After detection, one must respond. A planned response is best, especially for large events. Some agents can only be controlled by a continuous response, as in the case of incorrect temperature controlled by mechanical systems.

5. Recover/Treat

When stages 1 to 4 fail, one can only recover, and where possible, treat damaged items. An important part of long-term recovery, however, is to learn from such failures and to improve the four previous stages. Many risk management programs begin in the light of such failures.

The six “Layers” around the heritage asset

Nested enclosures

Perhaps the most ancient concept for risk management of precious artifacts was the strong box within the strong room within the strong building, situated on an easily defended site. Combined with the larger perspective of the geography within which the heritage asset is situated, we obtain the framework of “layers” shown below.

1. The region

The region is the location of hazards that we cannot avoid, but which we must understand, predict, and then mitigate appropriately.

2. The site

The site is the location of outdoor hazards, but for which we have some degree of control: drainage, lines of sight, road surfacing, barriers, etc. In many cases the site is part of the heritage asset.

78 3. The building

The building is the fundamental built layer around any collection. In many cases it is also part of the heritage asset.

4. The room

The room is often the location of special controls as well as new hazards.

5. The fittings

The fittings are the first movable layer, often part of a transition in responsibilities between the facilities manager and the conservator.

6. The packaging and support

The packaging and support are the closest layers to the heritage asset, always intended as protective, but they may also be a source of new hazards.

Not all heritage assets have all layers

Even when heritage assets incorporate only some of these layers, this framework can be useful to stimulate thinking about protection layers around the heritage asset.

Layers as hazards and as a structure for knowledge

Layers not only structure the analysis of the block stage of control, they also structure possible sources of hazards and agents of deterioration. For example, while each layer can block water or pollutants or fire that originates outside that layer, the layer itself can be the source of all those agents. The building can block regional rainfall but be a source of water leaks.

The layers also structure the knowledge needed for analysis: for each layer, there will be a separate body of knowledge and expertise.

The three sources of knowledge

For risk identification and analysis, there are three sources of knowledge. Conveniently, these map closely (though not perfectly) to the three types of risk occurrence, as noted in the middle row of this table 8.

Table 8. The three sources of knowledge for risk assessment.

Regional statistics Local knowledge Scientific and technical knowledge

These statistics are the bedrock of understanding catastrophic risks. Many agencies around the world have developed vast resources to provide non-technical users with Internet tools to predict these risks.

This source of knowledge needs you to meet people, to discuss, to interview, and to do facility surveys,

collection surveys, site surveys, etc. Do not underestimate or

overestimate this source relative to the other two.

This source includes the common sense and intuition of you and your colleagues.

The CCI web page on agents of deterioration provides an introduction to the essential understanding of each agent. Beyond that, one needs to read more or talk to experts (such as those at the institutes responsible for this manual).

This is the usual source of knowledge about the frequency and intensity of rare events.

This is the usual source of knowledge about common events and about the intensity of cumulative hazards. The source of knowledge about all five stages of control and the local layers.

This is the usual source of knowledge about the

sensitivity of heritage assets to cumulative processes and the source for most theories that can analyze risks.

Examples:

Geographic information systems (GIS)

Climate tables

Natural disaster statistical data

Government statistical data Shared data between heritage organizations

Examples:

Facilities surveys Building documentation Institutional memory Staff knowledge

Memory of local residents Observations of previous damage

Examples:

Technical literature Science literature

Building design documents Technical and scientific experts

Comprehensive risk identification: The Ten Agents and Three Types of Occurrence Table

{10 agents} x {3 types of occurrence}

If your task is comprehensive risk assessment, then Table 9 is a suggested list to “fill in.” It uses the 10 agents and the 3 types of occurrence. This gives 30 combinations, but in practice, a few are generally not applicable.

Table 9. The Ten Agents and Three Types of Occurrence Table. Expand the row widths so that the table fills the page when using it as a paper form in the field.

Rare events Common events

Cumulative processes

Physical forces Thieves and vandals

Fire Generally not

applicable Water

Pests Pollutants

Light, ultraviolet and infrared

Generally not applicable Incorrect Temperature

Incorrect relative humidity Dissociation

At least one risk per cell

The purpose of this table is not to limit the number of risks of each type — you may find many risks in a single cell. The purpose of this list is to encourage the assessor to think outside the usual habits. If one’s initial reaction is “I have no risks of this type” or “this makes no sense to me,” then imagine something unlikely or strange. You can always dismiss it later if analysis shows it to be very small.

The list can be shortened later

Some risks will be aggregated into one larger risk for assessment, either in this step or in the analyze step. Some risks will be shown by a preliminary analysis to be negligibly small. In the final report, there will always be the opportunity to note such revisions and their reasons. Be sure to make notes of all the ideas that arise during the identify step.

Comprehensive risk identification: Use efficient paths for surveys

Introduction

If you have limited access to the facilities and collections because of security or timing issues, then an efficient method for making surveys is essential. For collections and buildings, we suggest the method outlined below. In large facilities, with many windows, many doors, many rooms, many fittings, many packages, and many items, focus on documenting one representative example of each type, plus any special cases that are relevant to the risk assessment.

1. Tour the site

One circuit of the site. Note topography, drainage, lighting, neighbouring buildings, perimeter security.

2. Tour the buildings and outdoor sculptures One circuit of each building, each outdoor sculpture:

 Look from a distance (relation of the item to the whole asset and to external hazards)

 Inspect from close-up (current state, evidence of prior damage) For functional buildings:

 Inspect the roof (step back to see)

 Inspect the walls (from close and far)

 Inspect the doors

 Inspect the windows

3. Tour the collection rooms One circuit of each room. Concurrently:

 Inspect the ceiling, overhead services

 Inspect the walls, external and internal

 Inspect the doors, external and internal

 Inspect the windows

 Inspect lighting, mechanical systems

4. Tour the fittings, packaging, supports, and items One circuit of each room. Concurrently:

 Inspect the fittings

 Inspect the supports

 Inspect the packaging

 Inspect the items

82 5. Tour the non-collection areas

One circuit of remaining spaces.

 Document mechanical rooms, rooms with water supplies, occupants, garbage, easy access, etc.

Figure 12. Suggested pattern for a survey of a collection within a building within a site.

Rare events and regional data

Start from common sense and local knowledge

Most of the rare events that need regional data are the “natural disasters” that we can easily imagine, such as floods, earthquakes, extreme vandalism. We can start to identify these kinds of risks simply based on what is plausible and from what we hear from staff and residents on historic events. Horror stories from heritage organizations around the world provide further inspiration — could that freak theft, breakage, arson, gas explosion, etc. happen to us too some day?? If not, why not?

Begin to collect regional data

Maps and data on the frequency and intensity of natural hazards are easy to find. These help risk identification. The careful collection of such probability and severity data,

however, can wait for the analyze step (where sources of such data are described in detail).

Focus on how rare events will unfold

For rare events, the main focus during the identify step will be trying to think how such events would unfold in your organization, based on local knowledge.

Events that start small and grow

Many rare and catastrophic events are initiated by an event that is neither rare nor catastrophic, e.g. a small electrical short circuit, a visitor tripping and falling down. The question becomes: will the event escalate? Will such a short circuit cause a small fire because basic electrical safety measures were ignored by an amateur case fabricator?

Will that fire spread because the cases and room are all flammable and no sprinklers are present? Is the tripping visitor likely to be in front of the most precious artifacts? Are they easily knocked down? Do they shatter easily? These details can be called

“magnifying factors.”

Events that start big

Other rare and catastrophic events do have rare and catastrophic initiating events, such as major floods, earthquakes, external firestorms, etc. The question again becomes:

what will happen next? Are the heritage assets above the water line? Are the item supports earthquake resistant? Can the most precious moveable items be moved quickly to safety? These details can be called “reducing factors.”

Collecting local knowledge

Collect local documents first

We suggest that a risk assessment begin with the acquisition of all relevant documents (beyond those already collected for the establish the context step), such as:

 Building plans

 Disaster plans

 Loan forms

 Incident registers

 Climate control records

Use of local documents for risk identification

Intensive study of these documents can wait until the analyze step, but a preliminary scan of these documents can provide useful suggestions for:

 Possible sources of hazards

 Contributing factors to risks

 Risk issues to raise with staff

 Places to look more carefully during the facilities, collections, and site surveys Collect staff knowledge

Staff are an essential source of information about past incidents — fires, thefts, leaks, etc. They can provide the “inside information” on actual routines and procedures that are not formally described anywhere and not necessarily visible when you do the facilities survey.

It is important to understand the roles and responsibilities of the staff, as well as their understanding of the practical realities of the organization. Often the type of information needed for risk assessment is considered sensitive, and staff might choose not to reveal it unless they are made fully aware of the objectives, outcomes, and expected benefits of the risk assessment.

Identifying risks by causes other than the 10 agents

Ambiguities when using the agents

“Many visitors will touch the costumes within reach in the display area, causing soiling.”

The question immediately arises: does this go under thieves and vandals (a mild form of vandalism) or under pollutants (the soiling)? The short answer is that it doesn’t matter, as long as it goes somewhere. When we go to analyze and treat ambiguous risks such as this, however, we will often need the methods of analysis from both agents. We may use the methods of analyzing thieves and vandals to think about the hazard (visitor volume, ease of access) and the methods of pollutants to assess the effects

(discoloration, chemical attack).

Overlapping agents

“Many visitors will touch the costumes within reach in the display area, causing soiling, or abrasions, or small tears.”

Does this go under thieves and vandals, pollutants, or physical forces? There are two options, both acceptable: place it under the agent that you expect will be the biggest consequence (effects of pollutants, effects of physical forces), or place it under the agent that is the single unifying hazard (thieves and vandals). Although visitors breaking the rules is a very mild form of “vandalism,” this agent will help us think through the analysis and treatment of the risk. The methods for estimating the frequency of touching of accessible items by visitors is exactly the same as for estimating the frequency of serious vandalism.

Complex events with multiple agents

In other words, big messy events. Disasters. Natural hazards. War.

Again, the guideline during the identify risks step is not to worry; capture the specific risk in whatever language and categories seems most appropriate. Most large events will fit under its primary agent — physical forces, fire or water.

Later, during the analyze, evaluate, and treat steps, it will become clear whether it helps, or not, to disaggregate large complex risks.

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